1. Field of the Invention
The present invention relates to a driving apparatus for an electrophotographic device and, more specifically, to a driving apparatus for the rollers and gears used in a duplex electrophotographic apparatus.
2. Background Art
A driving mechanism for an electrophotographic device may be constructed using a pickup roller to load a sheet of paper from a paper stack into the electrophotographic device. Rollers then convey the paper to a developing unit that is positioned along the paper transport path. An electrostatic latent image is formed on a photoconductive drum that is turned into a latent toner image by the developing unit. The latent toner image is transferred to the sheet of paper when the paper passes through the photoconductive drum and the transfer roller. The toner image is then fixed onto the sheet of paper when the sheet passes between a fixing roller and a heating roller. The sheet then passes by a set of delivery rollers that apply a turning force on the paper causing one end of the sheet of paper to revolve around an inversion guide. For simplex, or one sided, printing, the sheet of paper revolves around the inversion guide and is ejected from the electrophotographic device via a pair of exit rollers.
For duplex, or double sided, printing, the sheet of paper passes around the inversion guide after having an image formed on one side. However, when the sheet passes through the inversion guide, a sheet sensor detects the paper and causes the exit rollers to rotate in reverse. This causes the paper to be fed along the paper transport path in a reverse direction. The sheet of paper passes through rollers and is fed to pickup roller 11. The rollers are driven by numerous driving motors.
Some techniques used in electrophotographic processes are shown, for example, in U.S. Pat. No. 5,666,611 to Chuan entitled Image Scanner With One Lighting Unit and One Drive System for Scanning Either Reflective or Transparent Objects, U.S. Pat. No. 5,148,220 to Hilbert entitled Toning Station Drive for Image-Forming Apparatus, U.S. Pat. No. 4,719,491 to Katoh entitled Copier, U.S. Pat. No. 5,584,589 to Adkins entitled Graphics Printer Roller Transport Apparatus and Method, U.S. Pat. No. 5,754,211 to Chung entitled Image Forming Apparatus With a Single Driving Source, U.S. Pat. No. 4,967,239 to Sakakura entitled Printer Having a Reversible Motor and Separate Transmissions Systems, and U.S. Pat. No. 4,743,975 to Ijuin entitled Image Processing Apparatus.
The driving apparatus used in image forming devices of the contemporary art use additional driving motors to control the various rollers that need to be manipulated during the duplex printing process. Thus, the internal structure of the electrophotographic device becomes more complicated, and an individual controller must be added to the housing for each motor employed. Furthermore, the manufacturing cost increases when multiple motors are used by one electrophotographic device.
As such, I believe that it may be possible to improve on the contemporary art by providing a driving apparatus for an electrophotographic device that uses only one motor to drive the paper controlling rollers, that is more economical to produce, that is easier to assemble, and that is simpler to repair.